Focus on alternative powertrain technologies for ICPC 2015

Every two years AVL organizes the International Commercial Powertrain Conference, a major event for the on- and off-highway commercial vehicle industries. On May 20-21, 2015, experts will meet in Graz, Austria, to share technology solutions and best practices to meet future market and legislative demands. Dr.-Ing. Marko Dekena, Executive Vice President, Global Business Development, Sales and International Operations Powertrain Systems, AVL, recently spoke with Managing Editor Jean Broge about some of the strategic and technical issues likely to be discussed at this year’s event.

This year’s ICPC is focused on “alternative powertrain technologies and innovations improving operating efficiency.” Can you put that focus in perspective in terms of technology advances and how they would apply to heavy-duty vehicles?

Basically the term “alternative” means any kind of powertrain solution for commercial vehicles different to that widely used today. In conjunction with efficiency improvements of new transmission designs, electrification and/or hybridization of the powertrain, or its components, as well as alternative fuels like CNG or vegetable oil fuels, are addressed. However, in terms of technology, every application has its own specific challenges as the operation modes are so different.

In truck applications, for instance, the dual-clutch transmission could offer not only reduced fuel consumption but also higher driver comfort. Partially this would be true also for agricultural tractors. Hybridization in trucks can save up to 10% of fuel even in long haul trucking—if properly made. In agricultural tractors, I do see electrification of auxiliaries and of some implements for improved efficiency and controllability. In construction equipment, depending on the kind of vehicle, hybridization can help a lot, especially in machines with very cyclic operating conditions. For all these new technologies and applications electronic system control and sophisticated software as well as the “right” shifting strategy is decisive.

What unique specifics of alternative powertrains would bring an advantage in particular to on-highway heavy-duty applications? Same question with off-highway applications?

For on-road heavy-duty vehicles the dual clutch transmission combined with a specific engine torque characteristic will bring the advantages mentioned above. Hybridization proved already up to 30% fuel savings in urban distribution traffic according to various investigations. According to our own simulation and tests, hybridization in combination with a proper engine downsizing can save up to 10% fuel also in long haulage. But also electrification of auxiliaries—water pump, oil pump, fan, and other “power consumers”—is good for another 2-3% simply by using them only when needed (“auxiliaries on demand”). And I would like to emphasize “waste heat recovery” to improve the thermal efficiency of the engine by up to 5% under full load conditions.

In off-highway applications the situation is much more complicated due to the heavily varying operating conditions. It is very important to define the benchmark technology. A full power shift transmission in agricultural tractors will show more efficiency advantages than a dual clutch solution, which is less costly. Many operations of an agricultural tractor will demand full powershift, a dual clutch solution would be simply not the right solution. Hybridization, both electrically and hydraulically, in CE can save up to 15-20% of fuel depending on the operating cycle. Therefore, for instance, wheel loaders, excavators, fork lift trucks, etc. will benefit from hybridization. In agricultural tractors the effect of energy recuperation by hybridization will be only small, but the electrification of auxiliaries and implements can enable significant savings depending on the kind of implement and the operation conditions.

Along the same line, where can on- and off-highway applications share alternative powertrain technologies?

That`s a very interesting question. In many of the previous ICPCs we discussed this question. Yes, there are possibilities to share technologies, and it is one of the key aims of ICPC to bring people of various industries together to learn from each other and to share their experience with the various technologies. Some were already mentioned: dual clutch transmission, hybridization and electrification. We also need to add exhaust emissions control and the aftertreatment system. Luckily we can use carry-over effects and experiences from on-highway vehicles, partially even from passenger cars. But never underestimate the efforts needed to adapt these technologies to the much more complicated and varying operation conditions of all off-highway vehicles.

One cannot just take a proven truck solution and implement it as it is into a tractor or construction machine. Packaging constraints are in many cases more severe than in trucks and redesigns will mostly be necessary. Moreover, the calibration of systems differs as well as needs for cooperation between the systems. Also software plays an important—and expensive—role, especially when taking into account the rather low production volumes of off-highway vehicles.

So, to say it with one sentence: alternative powertrain technologies can be shared to a certain extent but every application calls for specific adaptations.

What technologies would make gasoline engines viable for on-highway heavy-duty commercial vehicles?

Another highly interesting question. Since the introduction of severe emissions regulations that increased complexity and cost for diesel-operated vehicles more than for gasoline-driven vehicles, this question must be posed.

I would like to differentiate between on-highway light-duty (LD), medium-duty (MD), and heavy-duty (HD) commercial vehicles. The main argument for diesel is the significantly better thermodynamic efficiency compared to gasoline engines. This means that for applications in the LD area, where fuel consumption is not that important, gasoline engines could basically be viable. For MD and even more for HD applications, where fuel costs count up to 35% of the total vehicle life-cycle cost (in LDs it is only 10%), every single percentage point of lower consumption counts. Here we have to acknowledge a major difference in terms of passenger cars: trucks have to earn money. The heavier the vehicle and the higher the yearly mileage, the more important is the fuel consumption.

There is also a second strong argument for diesel engines in commercial vehicles: reliability and durability. With CV engines, European users expect an engine life until first overhaul of 1.2 million km (750,000 mi) in a HD long haul truck, and up to 800,000 km (500,000 mi) in MD trucks. No gasoline engine of today`s design would achieve this.

And as practical prove of this statement, you cannot find gasoline engines anywhere in MD and HD commercial vehicles, with two exceptions. U.S. MD trucks up to about 8 ton (7 t) are sometimes equipped with gasoline engines, but these are rather LD trucks according to European understanding. And in Russia there are even some HD vehicles with gasoline engines due to the need of easy cold starting and operation reliability under severe cold ambient conditions.

Is there a place for heavy-duty gasoline engines in the off-highway market, especially considering their varied duty cycles?

Gas engines of various forms are in service in many applications. The technologies used are well known and basically applicable to on- and off-highway. Here we have to answer the question of infrastructure. Wherever gas can be refilled easily, gas engines can and will be used to a certain extent. But what about construction equipment? In this business you never know where your machine will have to work. It is difficult to install gas filling stations somewhere in the country and one would not do it except in very large and long-time construction sites. The gas powered machines could only be used when proper gas supply is secured. In agricultural tractors the situation is more friendly as most of the vehicles return to their home base where a central gas filling station could make sense.

How easy, or hard, do you think it would be for end users and operators to accept a gasoline engine in their traditionally diesel-powered vehicles? How could they be swayed/convinced?

In my opinion and according to my personal experience it would be very hard if not impossible. The main arguments were already given in the answer before. Not to forget that truck operators, CE operators, and farmers are rather conservative clients. Generations grew up with diesels. And there are no real good arguments for MD and HD gasoline-powered commercial vehicles but there are many for diesel.

What are some of the challenges for the industry and heavy-duty engineers in particular in meeting Stage 5?

The European Commission just recently proposed a three-step introduction depending on engine power categories. In this proposal, the category 19 to 56 kW (25 to 75 hp) will be the one with major challenges and the shortest time available. In my opinion it is even extremely short, basically only three years would be available for the adaptation of these engines. With NRMM [non-road mobile machinery] the situation is much more complex than with on-highway vehicles due to the huge variety of applications and operating conditions.

The currently proposed strict regulations will significantly influence the required and applied technologies. Especially the foreseen particulate number regulation for all engine power classes between 19 and 560 kW (25 to 750 hp) will most probably demand wall flow filters.

However, many technologies required to meet the limits are basically known—flexible and high-pressure fuel-injection systems; turbocharging; internal and external EGR, DOC, POC, DPF, and SCR technology; and the respective electronic controls, you name them—they have been developed already for several on-highway and some off-highway applications in the past.

But, many of the above mentioned high-tech technologies can hardly be applied to engines and machines in the power range 19 to 56 kW (25 to 75 hp), not to speak about the tremendous cost impact. Maybe pre-chamber technology offers some advantages, but only very few manufacturers have them (still) in their programs.

There is not yet experience with many of the mentioned systems on very small engines. We will have benefits from the work done for on-highway vehicles, but we must not underestimate the specific adaptation work for small, low-power engines and the respective machine operating conditions.

Can you talk about how the potential increased use of advanced alternative and/or renewable fuels could have an impact on current combustion and aftertreatment systems? What about other heavy-duty systems and components? What needs to change?

Very difficult to answer this question. It all depends on the kind of alternative fuel. Let`s concentrate on renewable fuels from plants and vegetable oils. First of all any of these fuels have to be esterified or hydro-treated to give them a similar combustion behavior to diesel fuel. Major problems are the different properties of the base oil of the various plants—there is no worldwide standard yet regarding the final fuel quality.

Engine performance very much depends on the fuel quality, in some cases early engine failures may happen due to coking and/or lubricant dilution. There is little experience with common-rail injection systems and vegetable oil fuels. Some rubber sealings in the fuel line must be changed because standard sealings are destroyed by some vegetable oils, also paintings of vehicle components may suffer from spoiled fuel. There seems to be higher wear in the engine bearings, oil change intervals have to be shortened, maybe special lubricants have to be developed.

Aftertreatment systems, especially particulate filters, may suffer and be blocked faster due to non-proper fuel quality. This problem may occur during operating conditions with low exhaust gas temperatures, e.g., with agricultural tractors during planting, mowing, or other low-load operations. So it could strongly depend on the work the tractor has to do.

Connected driving is one of the ICPC 2015 tracks. What kinds of technologies will be addressed?

Connected driving—nowadays a hype in the passenger car world—is already utilized in some higher power agricultural tractors, mainly in the U.S., to enable precision farming. Huge fields are operated precisely by GPS-controlled vehicles, fertilizers are sprayed computer controlled according to the field conditions. Basically the vehicle is operated autonomously, the driver mainly has safety functions.

In the future, such systems will also be extended to smaller tractors for certain work where computer control is more efficient and precise than human control. In construction equipment there are also many operations that can benefit from connected driving/operating, e.g., optimization of loading-driving-dumping with the aim of achieving lowest fuel consumption with highest moved tonnage. Remote control of many construction machines (operator is outside of the vehicle) under specific working conditions is already widely used today.

Also in trucks connected driving has been used for many years—mainly to optimize the transport efficiency by logistics control. Autonomous driving of trucks is in the very focus of all major truck manufacturers but still in an advanced research status.

Can you speak in particular to “predictive controls?”

Predictive control of a vehicle is a rather new technology and not yet applied in series production. This technology is associated with hybridization and battery charging control. Via GPS and topography information discharging and charging of the battery is made depending on the topography ahead of the vehicle. During uphill driving the battery is discharged to a defined minimum to subsequently charge a maximum of electric energy during downhill driving and braking. This allows the application of smaller and therefore less expensive battery packs. Of course the same technology can be used on standard vehicles to optimize gear shifting and average speed of the vehicle. Many further usages of this technology will appear within the years to come.

Where is the on-highway heavy-duty industry at in terms of the connected vehicle timeline?

To some extent it is already there as mentioned before. But on a larger scale and including also autonomous driving it will take the industry at least 10 years. We must not forget that besides the technology itself there are many challenges to be faced: suitable infrastructure, worldwide standards, safety development and regulations, legal questions, etc. And it will also need quite some time to convince operators and the public.

What about off-highway vehicles and systems in terms of connectivity? Are the technological enablers already in place?

As mentioned before, partially yes. But the full potential is by far not yet exploited. Still, many vehicles and machines are controlled mechanically. With the degree of full electronic control of engines, transmissions, air conditioning, and other onboard systems, implements, hydraulics, etc., the degree of connected operating will increase.

What are some other technological breakthroughs or paradigm shifts (i.e., materials advances, testing & simulation techniques, manufacturing breakthroughs, etc.) that you believe will be necessary for future advances in heavy-duty engine performance and efficiencies?

In the truck area certainly further significant improvements of transport efficiency will be necessary. That means improved thermal efficiency of the engine beyond 45%, compact and lightweight designs of all main truck components, partially by use of new materials, significant reduction of air drag and rolling resistance of the vehicles, maybe higher allowable loads and longer truck-trailer combinations.

Simulation will become decisive and probably even more important than testing. All systems, especially with hybrids, will become increasingly complex, so that only sophisticated, model-based simulation tools and high expertise will help to keep development efforts in reasonable limits. This is true for trucks, but even more for tractors and construction equipment as their production volumes will stay relatively low also in the future, unfortunately with no reduction of the huge variety of applications and operating conditions.

Is there anything you would like to add?

I would like to add a clear invitation to join ICPC 2015 as this is the only conference worldwide to bring together all the three industries—trucks, tractors, construction equipment—simultaneously in one conference at one place which has reached a successful track record of already 15 years.

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